Production of aluminum chloride and alumina



APIll 18 1933- s. s. svENDsEN PRODUCTION OF ALUMINUM CHLORIDE AND ALUMIN Filed May 13 19274 QM En Patented Apr.- 18, 1933 t UNITED STATES' `SVEN!) S. SVENDBEN, 0F CHICAGO, ILLINOIS, ASSIGNOR TO CLAY REDUCTION COMPANY,

PATENT OFFICE OF CHICAGO, ILLINOIS, A CORPORATION 0F ILLINOIS l'ltonucfrlor4 or ALUMINUM cHLoRIDE AND ALMINA Application led Iay 413, 1&2?, Serial No.

This invention relates to theproduction of aluminum chloride and alumina' from aluminum compounds. The invention further relates to the production of hydrated silica and a residue high in soluble potash;

According to the invention raw material containing aluminum, and ordinarily silica, and sometimes potassium oxides, is converted into ammonia silicon fluorine compounds and metallic fluorides, preferably by the action of ammonium fluoride or bifluoride. On heating, the ammonia-silicon-fluorine compounds, together with titanium compounds and vanadium compounds, if any, sublime and the metallic fiuorides, particularly those of aluminum and potassium remain. Ammonia is evolved vand is collected. The sublimated ammonia-silicon-fluorine compounds are treated with water and ammonia, yielding hydrated silica and ammonium fluoride which is Washed out and recovered. The metallic fiuorides are treated with dry hydrochloric acid gas and ammonia at high temperature, thereby converting them into chlorides. Aluminum chloride and ammonium fluoride are volatilized and separated, the ammonium fiuoride being recovered. In this reaction the hydrogen chloride gasl is the effective agent in converting the metallic fiuorides into chloride. The ammonia is effective in converting the liberated hydrogen fluoride into ammonium fluoride.

The aluminum chloride may be converted into alumina by the action of water, if desired; hydrochloric gas is evolved and is recovered.

'The ammonia, ammonium fluoride and hydrogen chloride evolved at different phases of the processare reutilized in the process, being augmented to replace Wastage. Itis necessary-to supply a substantial quantity of hydrochloric acid gas for each run of the process since chlorine is taken out of the reaction in the residual metallic chlorides and also in the aluminum chloride, if it is not converted into alumina. 4

Suitable raw materials for the process are' bauxite, particularly White bauxite, and clay with low content of iron oxide; lime and soda. (lhina clay and fire clay are suitable. Clays 191,267, and in Norway October 25, 1926.'

containingundecomposed or partly decomposed orthoclase feldspar may be used. These hydrated silica. 4

The invention will be more fully understood from the following detailed examples:

Eaample I .-Dried clay 'containing feldspar is mixed, in hollanders, with ammonium fluoride solution containing suflicient fluorinel to convert the silica into silicon-diammino tetrafluoride (SiFNHQZ), and the metallic oxides into fiuoride's. The mixture is heated to between 34 and 100 C. The am monium fluoride is thereby dissociated into ammonia and ammonium bifluoride; the lat-I terl attacks" the clay, reforming normal fluoride which 4is again decomposed. Ammonia gas is evolved and recovered# The final result of this reaction is principally ammonium silicofluoride (NH4) 2SiF) metallic fiuorides and metallic oxides.

The 'mixture is evaporated to dryness; the ammonium silicofluoride gives off one-third of its fiuorino content, which completely con# verts the metallic oxides into fluorides. The

of Water and ammonia at a temperature maintained below 34 C., to yield-ammonium4 Alumina Silica fluoride and hydrated silica. The ammonium fluoride is removed by water and is recovered. After the volatilization of the ,volatile fluorides the temperature of the metallic luorides is raised to about 400 to 500 C. and a reducing gas is passed through same in order to displace any volatile fluorides yand to reduce any ferrie compounds which may be present. If ferrie compounds were not reduced, ferrie chloride would be formed in the next stage of the process and would contaminate the aluminum chloride and alumina derived therefrom. A mixture of ammonia gas and hydrogen chloride gas free from moisture, free oxygen and carbon dioxide is now introduced into the uorides.

These gases react on the metallic fiuorides forming metallic chlorides and ammonium iiuoride.' The aluminum chloride and the ammonium fluoride distill off leaving a residue of mixed chlorides including potassium chloride which is well suited for use as a fertilizer without further processing.

The mixture of vaporized ammonium fluoride and aluminum chloride is cooled to between 200 and 300 C., whereupon the ammonium fluoride solidifies and falls out. The aluminum chloride is cooled below its boiling point (187 C.) and is condensed and collected. The aluminum chloride may be converted into alumina, if desired.. The hydrolysis may. suitably be effected by steam, thereby producing aluminum hydroxide with two molecules of water and hydrochloric acid gas which is recovered.

The alumina is now calcined, losing one molecule of water at about 300 C. and the second moleculeat about 1000 C.

'The hydrochloric acid'gas is dried by sulfurie acid, the diluted sulfuric acid being used for the production of hydrochloric acid gas which isconsumed i'n the process.

The quantities of reagents used and prod` ucts producedfwill naturally depend upon the quantity and. composition of the initial clay. For example, assuming 120 tons of clay of the composition Ferrous oxide Lune Pota sh then a solution containingl 262 tons of ammonium fiuoride will be required to convert the-silicon into siliconfluoride-ammonia and the metallic oxides into metallic fluorides in the next phase ofthe process. In this part of the process 79.2 tons of ammonia gas are evolved and 165.6 tons of silicon iiuoride ammonia are volatilized. The siliconiluorideammonia is deomposed by 40.8 tons ofam- 'monia and 172.8 tons of water, forming 177.6

tanic iiuoride.

tons ot ammonium fluoride and hydrated sil-v quired. The residue of mixed chlorides is 31.2 tonsA containing 7.2 tons or 23% potash (as KgO).

The ammonium fluoride here recovered amounts to about 81.2 tons and together with theammonium fluoride recovered. from the hydratedsilica substantially equals the ammonium fluoridev used in the iirst step of the process. The yield of aluminum chloride is about 78 tons. l

The hydrolysis of this amount of aluminum chloride requires about 26.5 tons of steam and yields 64.4 tons of hydrogen chloride gas which is dried by sulphuric acid and is used in the conversion of another batch of metallic fiuorides into chlorides being augmented by about 17.6 tons hydrochloric acid gas, which corresponds to the amount required for the formation of the residu-a1 metallic chlorides. v

' The amounts of ammonia gasrequired for the formation of the hydrated silica and the conversion of metallic iuorideinto chlorides are substantially equal to the amlnonia is therefore necessary only to replace wastage. Wastage of fiuorine can be compensated by addition of fluor-spar to the'mixture.

Example I I .--Bauxite is finely ground, reduced if necessary and a solution of ammonium fluoride is added and the mixture heated above 34 C.; for example, between 34 C. and 100 C. The water is then evaporated and the silica is converted into ammonium silicofluoride, andV any titanic acid present is also converted into ammonium ti- `monium silicofiuoride being converted-int silicon-diammino tetrafluoride i (SiF4(NH3)2).- The ammonia evolved is collected.

On completion of this reaction the temperature 1s raised to about 300 C. to volatilize the volatile iuorides, principally the ,silicon-u diammino tetrafluoride, titanium and vana. dium fiuorides, etc. The volatile iuorides are completelyl displaced by passage of reducing gas through the residue. The reducing gas may suitably be producer or' water gas carefully treated forv removal of free oxygen,l

water and carbon dioxide. The gas is passed The ammonium iuoride is "n'unlilbride and the alumina derived therethrough'while the mass is at an'incipient red heat, for example, between 400 and 500 C.

from.

The volatilized fluorides, principally silicon-diammino te'tr-afluoride are precipitated by cooling and are treated with aqueous ammonia below about 34 C. lbeing thereby converted into hydrated silica and ammonium fluoride. The ammonia used may be part of that evolved in the first part of the process. The ammonium fluoride is washed out with water and is 4used in the first step of a subsequent batch. The hydrated silica is dried to give a commercial product.

The unvolatilized fluorides, consisting principally of aluminum fluoride, are treated at between 400 and 500 C. with an equi- .molecular mixture of hydrogen chloride gas and ammonia vapor from which moisture, free oxygen and carbon dioxide have been eliminated. The metal fluorides are thereby converted into chlorides and ammonium fluoride is produced. The ammonium -fluoride and the aluminum chloride volatilize. The former is preci itated by cooling to between 200 and 300 and the latter is condensed by cooling it below its boiling point.

As in Example I the ammonium fluoride used in the process is recovered completely' except for mechanical losses and the ammonia evolved is reused in the same run. In general, a loss of hydrogen chloride is involved in fr\convertingthe.residual-metallic compounds into chlorides.

Amounts of reagents which are used and the amount of reaggitsand productse4 Veredmdepend/pci the composition of the aluminous containing raw material as will be completely understood from Example I.

While it is preferred to use ammonium fluoride or hifluoride for the production of fluorides in the reaction mass it must be understood that it is not intended to limit the process thereto since such production can be effected by the use of hydrofluoric acid or in other known manner. The method described has, however, outstanding advantages. For example, the production of the annoying and poisonous fumes of the hydrofluoric acid and silicon fluoride are thereby avoided. Furthermore, ammonium fluoride has only a slightly corrosive action on metals and does not attack the skin. An outstanding advantage in the use of ammonium fluoride is that it is' regenerated completely, except for mechanical losses, during the process.

`Although the present invention has been described in connection with the details of s cific examples thereof, it is not intended t at such details shall be regarded' as limitations u on the scope of the invention, except in so ar as included in the accompanying claims.

The accompanying flow sheet will serve to more clearly illustrate the process.

Iclaim:

1. The. method of producing anhydrous aluminum chloride which consists in treating aluminum fluoride with hydrogen chloride and ammonia as.

V2. The met od of producing anhydrous 'aluminum chloride which consists in treating aluminum oxide with a reactive fluoride, thereby forming aluminum fluoride and treating the fluoridewith hydrogen chloride and ammonia gas.

3. The method of producing aluminum chloride from material containing aluminum oxide and silica, which consists in treating said oxides with a reactive fluoride, thereby forming corresponding fluorides, volatilizing the silicon as a fluorine compound, and treating the aluminum fluoride with hydrogen anda volatile alkali, `thereby forming aluminum chloride and separating it from impurities by distillation. v

4. The method of producing 'aluminum chloride from material containing aluminum oxide and silica, which consists in treating said oxides with ammonium fluoride, thereby formingammonia-silicon-fluorinecompounds and aluminum fluoride, heating the mixture to volatilize the ammonia-siliconfluo'r'ine compounds, and reactmg'on the alummum fluoride with hydrogen chloride in the-presence of a volatilealkali, thereby forming aluminum chloride.

5. The method` of producing aluminum chloride from material containing oxi des 9f silicon, aluminum'f'and other metals which Vconsists in treating said material with ammonium fluoride to form ammonia-silicon- 'fluorin'e compounds, aluminum fluorides and fluorides of other metals, heating the mixture to volatilize the ammonia-silicon-fluorine compounds, and subjecting the fluorides of aluminum and other metals to the action of hydrogen chloride in the presence'of a volatile alkali, thereby forming 'corresponding yanhydrous chlorides.

6. The method of producing aluminum chloride from material containing oxides of silicon, aluminum and other metals whichv consists in reacting `on said material with ammoniuml fluoride to form ammoniasili-v con-fluorine compounds, aluminum fluorldes and fluorides -of other metals, heating the mixture to volatilize the ammonia-siliconfluorine compounds, heating the fluorides of aluminum and other metals with ammonia and hydrogen chloride acid to convert the fluorides into chlorides and to produce ammonium fluoridev and volatilize Valuminum A chloride and ammonium fluoride, cooling to 5 coolin to condense the aluminum chloride.

7. e method of producing aluminum chloride from material containing oxides of silicon,-aluminum and other metals which consists in treating said material with ammonium fluoride, heating the mixture to produce ammonia-silicon-luorine compounds and metallicvfluorides and to volatilize the ammonia-silicon-fluorine compounds `from the metallic fluorides, heating the lluorides of aluminum and other metals with ammonia and hydrogen chloride to convert the lluorides into chlorides and separating the aluminum chloride from the other chlorides by distillation.

8. The method of producing aluminum chloride-trom material containing oxides of silicon, aluminum and other metals which consists in treating said material with ammonium fluoride, heating the mixture to produce ammonia-silicon-fluorine compounds and metallic luorides and to volatilize the ammonia-silicon-luorine compounds from the metallic lluorides, heating the fluorides of aluminum and other metals with ammonia and hydrogen chloride to convert the fluorides into chlorides and to produce ammonium fluoride.

. 9. The method of treating material containing oxides 4of silicon, aluminum and potassium with ammonium fluoride -to convert such oxides into useful compounds and recover the ammonium fluoride which consists in mixing the material with a solution of ammonium fluoride, heating above 34 C., evaporating the waterY and heating to about 300 C. to produce and volatilize ammonia-silicon-fluorine compounds, raising the temperaturep themresidue to' 400-500 C. and treating with anhmlydrogen-chloiithagas and ammonia thereby converting the meiimk luorides into chlorides, producing lammonium fluoride, and volatilizing the aluminum chloride and ammonium fluoride, condensing the ammonium fluoride bycooling and condensing the aluminum chloride by further cooling. l 0

10. The method of treating-material containing oxides of silicon, aluminum, iron and vpotaiumv with ammonium fluoride to "con- Avert such oxides into useful compounds and recover the ammonium fluoride which consistsinmixing the material with a solution of ammonium luoride, heating above 34 C.,

Y evaporating the water and heating to about 300 C. to produce and volatilize ammoniay silicon-luorine compounds, raisin'gthe tem-- perature of the residue to JMP-500A C., 'reducing with an anhydrous reducing gas and treating with anhydrous hydrogen chloride` A .gas and ammonia thereby converting the metal il-uorides into chlorides, producing ammonium fluoride, and volatilizing the alumi- 'num chloride and ammonium fluoride, condensing the ammonium fluoride by cooling tion.

g ammonium fluoride, and" further cooling to and condensing the aluminum chloride by further cooling. Y

to form aluminum fluoride and treating the fluoride with hydrogen chloride and ammonia gas While heating to a temperature of 400 t0 500 C. i

14. The method of producing anhydrous aluminum chloride which comprises reacting on aluminum oxide with a reactive fluoride to form aluminum fluoride and treating the fluoride With equimolecular proportions of hydrogen chloride and ammonia gas while heating to a temperature of 400 to 500 Cl c I 15. The method of producing aluminum chloride from material containingl oxides of silicon, aluminum and other metals which comprises reacting on said material with ammonium fluoride .to form ammonia-siliconfluorine compounds, aluminum luorides and fluorides of other metals, heating the mixture to volatilize the ammonia-silicon-tluor-A ine compounds, treating the lluorides of aluminum and other metalsvvith ammonia and hydrogenV chloride. at a temperatur/e of 400 to 500 C. to convert the fluorides into 105 chlorides Vand separating the aluminum chlo-v A ride from the otherV chlorides by-volatiliaa- 16. The method ofproducing aluminum chloride from material containing oxides of 110 silicon, aluminum and other metals which comprises reacting on said material with ammonium fluoride to form ammoniasiliconluorine compounds, aluminum luorides and lluorides of other metals; heating the mixture to volatiljze the ammonia-silicon-fluorine compounds, heating the residual iluorides with ammonia -and hydrogen chloride at a temperature of v400 to 500 C., 'thereby-converting the iluorides int chlorides, producing ammonium fluoride, and volatilizing aluminum chloride fand ammonium fluoride, cooling the evolved vapors to condense the condense the aluminum chloride.

17. The method of producing av purified' anhydrous aluminum chloride lfrom fmaterial containing iron and aluminum-which Teomprises subjecting the material .ito-theaction of a reactive lluorideto convert themetallic 13 content thereof to fluorides, heating the converted material inthe presence of an anhydrous reducing gas and treating it with hydrogen chloride at an elevated temperature in the presence of a volatile agent capable of reacting with the hydrogen fluoride formed,

Vthereby forming aluminum chloride and volatilizing the latter substantially free of iron compounds.

18. The method of producing aluminum chloride from material containing aluminum oxide, silica andiron impurities, which consists in reacting on said material with ammonium fluoride to form ammonia-siliconiiuorine compounds and aluminum fluoride, heating'the mixture to volatilize the ammonia-siliconfluorine compounds, heating the residual uorine compounds in a reducing atmosphere to reduce theerric iron content thereof, and thereupon treating them with hydrogen chloride at an elevated temperature-in the presence of an agent capable of reacting with the hydrogen liuoride formed, thereby converting the aluminum fluoride into aluminum chloride.J

19. The method of producing a substantially iron-free aluminum chloride from materials containingxides of silicon and aluminum and iron impurities which comprises treating said material with ammonium liuoride, heating the mixture to produce am, monia-silicon-luorine compounds and metallic uorides and to v'olatilize the ammoniasilicon-iuorine compounds from the metallic n luorides, further heating the mixture in the presence of a reducing atmosphere to reduce the ferrie iron compounds resent, and thereupon treating them with ydrogen chloride at an elevated `temperature in the presence of a volatile agent capable of reacting with the hydrogen iuoride formed, thereby converting the metallic iluorides into chlorides andl separating the aluminum chloride from the other chlorides by distillation.

20.- The method pf producing a purified' anhydrous aluminum. chloride from material containing iron and aluminum which comprises subjecting the material tothe action of a reactive fluoride to convert the metallic content thereof to fluorides, heating the converted material in the presence of an anhydrous reducing agent and treating it with hydrogen chloride and ammonia at a tem+ perature of-at least about 4009 C., thereby forming aluminumchloride and volatilizing the latter substantially free of iron compounds. Y

21. The method of producing aluminum chloride from-material containing aluminum oxide, silica and iron 'impurities,which consists in reactin on said material with am'- monium fluori e to form ammonia-silicon- 'luorine compounds and aluminum fluoride,

heating the ,mixture to aolatih'ze the ammomia-silicon-uorine compounds, heating .-v 

